Aeroplane propeller



W. LINDSAY.

AEROPLANE PROPELLER. APPLICATION FILED JUN-E19, 191s.

Patented July 4, 1922.,

Jimm

P i hi i WILLIAM LINDSAY, CHICAGO, ILLINOIS.

AEROPLANE PROPELLER.

- To all w 710m it may concern:

by the thrust and drift forces, will be greatly decreased, the thickness or volume of the blades consequently reduced, and ,an improved mode of operation of the blades, resulting in high increase of the efficiency of the propeller attained.

Another object is to provide a strong, durable, and conveniently manufacturable and utilizable propeller, wherein the blades are interchangeable and may be individually replaced in case any damage occur to any one of them.

In carryin out the invention. individual blades are independently pii'oted to the hub of the propeller in such manner that they may be also secured to the hub against swinging, so as to be converted into a rigid propeller. hen the blades are in pivoted state, they will during rotation of the propeller dispose themselves alonga line which .35.. .is the resultant of the centrifugal and thrust forces, in which position they may also be permanently secured to the hub, and in either of which cases the cross-sectional strains will be minimized, the great reduction of the thickness of the blades rendered possible, and the resulting efiicieney of the propeller secured. The blades are also disposed along a line which is the resultant of the centrifugal and drift forces, which further minimizes the strains and results in a consequent reduction in the volume of the propeller and a further increase of the efli ciency thereof.

As a result of the stated disposition of the blades, their cross-sectional area may be reduced to such an extent that it enables constructing the entire propeller of metal, and thereby affords the various advantages which a propeller of metal would have .over a wooden propeller, such as increased efficiency, inherent strength, and durability.

Specification of Letters Patent.

Patented July 1, 1922.

Application filed June 19 1918. Serial No. 240,745.

Other objects and advantages will hereinafter appear.

In the accompanying drawings,

Fig. 1 shows a side elevation of the aeroplane propeller.

Fig. 2 shows a plan view of the propeller shown in Fig. 1.

Figs. 3, 4, and 5 show modifications of the propeller.

The drive-shaft 1 of the aeroplane carries a hub 2 provided with two pairs of ears 3, and between each pair of cars is lodged the extremity 4 of the base 5 of a propeller-blade 6. A bolt 7 passes through each pair of ears 3 and through the extremity 4 of its blades 6, whereby the blade is pivotally held to the hub 2 and is swingable about its bolt 7 toward and away from the direction of flight of the aeroplane. For each blade 6 is provided a spring 9, which is secured to the hub 2 at 10 and also to the blade at 8, thereby maintaining said hen the propeller is in operation, the centrifugal force tends very strongly to maintain the pivoted blades 6 revolving in a plane which is rightangular to the direction of flight, while on the other hand the thrust tends to swing the blades in a direction which is similar to the direction of flight, and the consequence thereof is that each of the blades becomes disposed angularly, as shown in Fig. 1, along a direction which coincides with the resultant of the centrifugal and thrust forces. Thus in Fig. 1, the arrow 11 represents the direction of flight, the dash and dot line 12, which is rightangular to the direction of flight, represents the direction and magnitude of the centrifugal force, the line 13, which is parallel to the direction of flight, represents the direction and magnitude of the thrust, and the line 14., which is the centre line of gravity of the blade 6 and completes the triangle with or the resultant of the complementary lines 12, 13, represents the resultant or actual disposition of the blade 6, when the propeller is revolving.

The effect of the above described action of the blades 6 during operation of the propeller, wherein each blade seeks independently its own plane of revolution, is to minimize greatly the lateral or cross sectional breaking strain at every part of the blade and particularly at its base portion 5,whereby the I thickness of the blade may be reduced to Such an extent as -to enable casting or forging the entire blade of metal, such as steel or other metal having a high tensile strength, and thus rendering the propeller practically indestructible under all conditions. Constructing the blade 6 of metal enables making further reduction in the thickness of the blade, and each reduction of the thickness of the blade conduces greatly toward increasing its driving efficiency, due to the reduction of the rotational resistance or, what; is termed, the drift of the propeller. The plvoted or, what may be termed,the independent flexible connection of each one of the blades 6 with the hub 2 tends to soften the gyrostatic action 'of the propeller, and results in eliminating considerably the strain caused thereby to the engine drive-shaft 1 and the friction of saidshaft in its bearings. When changing the direction of flight of the aeroplane each spring 9 aids in forcing its blade 6 into the new plane of revolution. This mode of connection of blades 6 with the hub 2 also lessens the shock to the propeller and aeroplane, caused by the sudden turnmg movement of the aeroplane' If desired, the blades 6 may be secured rigidly to the hub 2, against swinging with relation thereto, in the disposition shown in Fig.1, by means of strongly tightening the forces 12,123, as an entirely bolts 7 and the nuts 15 and thereby compelling the ears 3 to forcibly ip the bases 4 of the blades, whereupon t e blades 6 will continuously remain in the direction of the resultant 14 of the centrifugal and thrust rigid propeller. In the direction ofi; revolution of the propeller, Fig. 2, the centre line of gravity of I coincides each of the blades 6, rather than being radial to the centre line of the drive shaft 1 as was heretofore the practice, is here disposed n y,

with the resultant. of the drift and centrifugal forces. Thus, in Fi' 2, the arrows 16 represent the direction 0 revolution,

, the line 17 which is radial to the centre line of the drive-shaft 1 represents the direction and magnitude of the centrifugal force, the line 18 represents the rotational resistance or drift, and the line 19, which is the centre line of gravity of.the blade 6 and completes the triangle with or the resultant of the'complementary lines 17, 18 represents the resultant or actual disposition of the blades 6. The effect of this dispositionof the blades 6 1s to further minimize, during rotation of the propeller, the cross-sectional breaking drift force strain at every part of the blade, and partlcularly at itsbase-portion 5, caused by the by the thickness of the blade may be further reduced and the various above mentioned advantages of such reduction obtained.

When making the individual blade 6 of as shown, along a'direction which or resistance to rotation, where-' as shown in Fig. 4, and the opening 20 between the split portions 21 may be filled with any light material such as wood, thereby increasing the width and consequently the stren th of the base-portion 5, so'that it may be thinned down further and the wellknown advantages of such reduction of thickness attained. Theb-lade 6 may be also made partially hollow at its base-portion 5, as shown in Fig. 5.

The modification shown in Fig. 3 illustrates the adaptation of the improvements herein to a three-blade propeller.

Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others.

Having thus described my invention, I claim I v v 1. An aeroplane propeller having the combination of a hub to a drive shaft, a plura ity of individual blades each of which is constructed of metal and each of said blades being split at its base land filled with lighter non-metallic materia '85 ada ted to be secured 2. An aeroplane propeller, having the the areoplane is at rest.

4. An j aeroplane propeller having the longitudinal centre line of-its vanesso disposed during. flight that it lies in the direction of a line which is the resultant of the torslohal and centrifugal forces, said vanes being pivoted to permit them to automati-' cally assume a position which is the resultant of the said two forces and also that of thrust, and said vanes beingv disposed in operative state when the aeroplane is .at rest. 5. An aeroplane propeller having the longitudinal centre line of its vanes so disposed during flight that it lies in the direction of a line which is the resultant of the torsional and centrifugal forces, said'vanes being pivoted to permit them to automatically assume a position which is the resultant of the said two forces and, also that. of thrust, sald vanes beingdisposed in operatlve state when the aeroplane is at rest, and meansto interchangeably secure said vanes to retainthem permanently in the resultant of the said three forces.

6. An -aeroplane propeller having the longitudinal centre line of its vanes so disposed during flight that it lies in the direction of a line which is the resultant of the thrust and centrifugal forces, means to permit said vanes to automatically assume a position which is the resultant of the said two forces, said vanes being disposed in operative state when the aeroplane is at rest, and means to interchangeably secure said vanes to retain them permanently in the resultant of the said two forces.

7. An aeroplane propeller having the com'binationof a hub adapted to be secured to a drive shaft, a plurality of individual blades each of which is pivoted directly to said hub without any intervening element and adapted to swing independently with"- out affecting any other blade, and a' spring for eachof said blades cooperating there- With individually to maintain it extended when in inoperative state.

8. An aeroplane propeller having the combination of a hub adapted to be secured to a'drive shaft, a plurality of individual blades each of which is pivoted directly to said hub without any intervening element and adapted to swing independently without afiecting any other blade, and a spring for each of said blades cooperating therewith individually to induce the blades in acquiring their new place of revolution when changing direction of flight.

9. An aeroplane propeller having the combination of a hub adapted to be secured to a drive shaft, a plurality of individual blades each of which is pivoted to said hub without any intervening element and adapted to swing independently without affecting any other blade,'a spring for each of said blades cooperating therewith individually to maintain it extended when in inoperative state, and induce the blades in acquiring-a new plane of revolution, said blades being adapted to automatically swing to a position that coincides with the direction of a, line which is the resultant of the centrifugal and thrust forces of the revolving propeller, means for each of said blades to fasten it independently to said hub in the said resultant position for operating the propeller with the blades in rigid condition, each of said blades being also disposed whereby its centre line WILLIAM LINDSAY. 

